[Live-devel] understanding the normalzerFilter in the ProxyServerMediaSubsession::createNewStreamSource

[Craig Matsuura]

Hi Ross,


I have a a question. I see in the ProxyServerMediaSubsession::createNewStreamSource, there is a normalizerFilter setup for the PTS times from a source. Why can't the PTS times from a source be used instead of normalizing it? Is this due to latency from proxying a camera stream?


      // Then, add to the front of all data sources a filter that will 'normalize' their frames'
      // presentation times, before the frames get re-transmitted by our server:
      FramedFilter* normalizerFilter = sms->fPresentationTimeSessionNormalizer
        ->createNewPresentationTimeSubsessionNormalizer(fClientMediaSubsession.readSource(),
                                                        fClientMediaSubsession.rtpSource(),
                                                        fCodecName);
      fClientMediaSubsession.addFilter(normalizerFilter);


In our case the proxy server is proxying a rtsp stream from a camera (rtsp stream). We are noticing that the when we pull from the stream the PTS don't seem to have the large jumps we see when going through the proxy. I did see your comment in the FAQ on the large timestamp jump and you said that is normal. Is this normal jump due to the normalization?


I have a colleague working on a DVR application and his source is from the proxyserver. He says he does not have issues with the PTS if coming direct from a camera only the proxy and sometimes the timestamps jump/change in the middle of his session (which I assume is a problem from the source).


So is the normalization needed for a source that has valid timestamps?


Thanks for helping me understand.


Craig
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